1. Field
The following description relates to ultra low power (ULP) wireless communications. The following description also relates to a method and apparatus for performing automatic gain control (AGC) in a ULP wireless receiver.
2. Description of Related Art
With the development of ULP wireless communications in application areas such as, for example, body area networks, wireless personal area networks, and wireless sensor networks, the design challenges in a ULP wireless receiver have increased. In such applications, the ULP wireless receiver provides low data rates, for example, less than 1 megabit per second (Mbps), while operating over short distances, for example, up to 50 meters, with minimal power consumption.
The ULP wireless receiver potentially experiences a high variation, for example, up to 100 decibels (dB), in received signal power at an antenna of the ULP wireless receiver due to multipath and shadowing effects. In the ULP wireless receiver, the operation and design of an AGC circuit is significant for successful demodulation of signals received at the ULP receiver. Generally, the ULP wireless receiver uses multiple variable gain stages between the antenna and an analog-to-digital converter (ADC). For error-free reception of packets and successful baseband demodulation, an output signal of the ADC has a relatively high signal-to-noise ratio (SNR) and an adequate amplitude variation. In response to incorrect setting of the variable gain stages, the output signal of the ADC saturates frequently or has a low SNR, resulting in unsuccessful demodulation.
In existing AGC designs for high throughput technologies such as, for example, wireless local area network (WLAN) communication and 2G/3G/4G cellular coherent wireless receivers, multiple inputs obtained from multiple observation points, for example, outputs of the ADC, an adjacent channel rejection filter, and a peak detect filter, are used. The operation of the AGC in these examples is complex due to stringent requirements on a convergence time, and aspects related to processing of data from the multiple observation points.